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[paparazzi-devel] Replies to posts on the digest

From: Hugo Vincent
Subject: [paparazzi-devel] Replies to posts on the digest
Date: Tue, 04 May 2004 20:59:52 +1200

Hi everyone,

I just thought I would give you an update on my UAV project: I am designing a Ground-station application at the moment, until I get my budgeting sorted out, and also things are really busy in the rest of my life at the moment, so I don't have time to do hardware stuff.

The ground station is being written in QT/Free, from This allows it to be multi-platform and run on Mac OS X (my operating system of choice) as well as linux/unix (or with a license, on M$ Windows... ). I would have built on top of an existing ground station, like the paparazzi one, but its inconvenient to use GTK and X11 on Mac OS, whereas QT runs natively (without an X server etc, straight on to the Mac OS X Aqua engine). I don't particularly like Java GUIs but that was the other main possibility. I am just learning C++ and QT at the moment, but I hope to have a beta suitable for consumption in a month or two. I have got to the point where the GUI is laid out (in QT Designer), and most of the 'glue' code to run the GUI is working (sortof :), and I am writing the 'back end', down links etc.
Any ideas/suggestions/requests?

At some point, I also want to build a link to JSBsim or FlightGear into it, for flight visualization when its in the air, and as a hardware in the loop simulator, when its on the ground. I am a little worried about how well JSBsim will handle simulating such a small plane, an low speeds and low reynolds numbers, and also how i will create and calibrate a flight model for it. Any ideas?

Cheers, Hugo.

Hi Antoine

Hi everybody

Hugo Vincent wrote:

Hi Steve,
Sorry for the confusion Antoine, the post was sortof addressed to Steve, but seeing as you suggested that I keep all communications that might be relevant to others on the mailing list, I did :)

I am working on a UAV project too; I haven't made a website yet, but have written and collected a fair bit of material in the attached PDF file ( ) -- but I am not sure how the mailing list system will handle it. (It's still in a state of change, so ignore anything that looks unfinished or wrong!) Please feel free to use the ideas in it, and consider releasing your work under
a GPL type license so we can all share

It's very interesting, but i think you'd better not send such big attachment to the list. You could put it somewhere on the the web and send a link to it.

If you like, we can host your document in the paparazzi CVS at savannah.
OK, that would be great, would it be possible for me to get a login to the CVS to that directory (I am not sure if you can do that?) so I can change it with out you having to update the CVS manually?

I have just looked at your website -- cool! I would like to know more about the airframe: did you design it? The specifications you came up with -- how where
they generated/based on?

I have been playing around with SolidWorks/COSMOSworks (3D Cad and analysis plugin that does stresses etc, and aerodynamics), and XFoil (GPL airfoil design tool and simulator) trying to design an airframe, and am getting fairly bogged down in it all! I must say, just from looking at your website, that you sort of just got out the tools and started making it, with out really doing the design
and calculations (no offense, I wish I could do that).

which airframe are you talking about ? The twinstar is a ready to fly kit from multiplex. We choosed this plane because it is well suited to our need : it flies well, doesn't need a runway, is very "heavy duty" and very cheap. Wing mounted motors have the advantage of protecting propellers during landing and
leaving the nose of the aircraft free (for the camera..)
I am already aware about your plane. I am still deciding if it will suit my needs, which it probably will, in which case i'll buy one shortly.

Also, for the airframe, especially the wings and tail-plane surfaces, you might want to investigate a technique called vacuum bagging, where you lay-up the foam with all the various composites, add an anti-stick film, put it in a sealed bag, and apply around 4-8 psi of vacuum pressure. Alternatively you can
use the parts of the foam that you cut the wings from ("negatives" or
something, sometimes called shucks), put your layed-up wing in them (with appropriate anti-stick protection) and puts weights on the shucks to apply pressure to the lay-up, increasing strength of the bond to the foam, and as a result, the strength of the whole wing, and allowing less epoxy to be used
(less weight).

The maxi kiool was build using this technique. We have almost abandonned this airframe, due to its fragility. Motor gears are not very well suited as landing
gear :)
lol :)

Message: 3
Date: 30 Apr 2004 20:48:12 +0200
From: Antoine Drouin <address@hidden>
Subject: Re: [Paparazzi-devel] (no subject)
To: address@hidden
Cc: address@hidden
Message-ID: <address@hidden>
Content-Type: text/plain
We have build a sensor with a tiny propeller driving a cell phone motor.
We amplify and measure the analog voltage produced. The sensor works
fine for the small speeds we fly (8-15m/s).
We have done nothing yet with these data.
Hmm, I am sure this works, but it doesn't sound like its the "optimal" solution. A pitot tube is much more elegant, more accurate, more reliable (no moving parts), is there a reason you haven't tried this. You can make one easily, with another pressure sensor attached to a tube facing forward at the front of the plane (in 'ram' air). There is a simply formula, but i can't remember it (something like V = 1/2 * [density of static air (dependent on altitude)] * [ram air pressure from pitot tube]^2 ).

Message: 8
Date: Sun, 2 May 2004 18:12:08 +0200 (MEST)
From: address@hidden
Subject: [Paparazzi-devel] conceptual design proposal (without IR
To: address@hidden
Message-ID: <address@hidden>
Content-Type: text/plain; charset="us-ascii"

The planned sensors are:
absolute pressure sensor TBD.
cheap and small condensator microphones to measure the wind speed TBD.
IR receivers 41 KH or similar on all sides grouped with correspondenting IR senders. OPTIONAL (formation flight and optical high speed comms using
cheap laser pointers)
Rain sensor SUGGESTED (pbc)
Radioactivity sensor OPTIONAL (led)
ELF sensor SUGGESTED (can be merged with motor)
TEMPEST sensor (high speed fft on a MCU required). OPTIONAL (can be merged
with elf sensor)
Current sensors for the follow items:
  - Overall current
  - Servos. TBD.
  - Motors  TBD
  - Goldcap TBD
Themperature sensors:
  - motors
  - battery
  - internal
  - external
  - electronic
  - high power/current electronic
  - thermal wind speed meter OPTIONAL
Voltage sensors:
  - battery
RPM using a transistor in order to measure the RPM of the single motors.
  This can be used to calibrate the wind sensors.

  - servos
  - reset or power interrupt devices OPTIONAL
- battery switch for optional reserve battery using step up converter.
  - laser pointer OPTIONAL

Storage for black box:
  MMC card. (SPI interface)

Open issues:
 - model plane for research and testing.
This need porting higher payload and must be a autonomy of minimal 40
   minutes at reasonable costs.
 - model plane for final implementation.
- cooling of battery inside the foam wings, i don't want using alluminium
   foil because it's reflects radar very well.
   The agreed altitude for a model plane is between 100 and 300 foot in
   the country i live. It's depends of the interpretation from the law
I simple don't want attract the attention, if i cross in the beginning
   of the radar height (150 foot).
 - I need the fasttrak firmware for GPS ? What is the cost ?
- How to optain the firmware for approximative 38K baud instead of the 4.8K
baud in order to got the 10 HZ update feature.
 - I need dgps ?

It's possible to merge the two project or to produce usable subsytems for
both the projects.

As attachement, i sent the planned overall structure of the SW.
I plann to use fuzzy logic or a rule system or neuronal logic or
genetic algorithm.
It's highly possible, that the resulting algorithm use a combination of
the previosly mentioned methods.
Currently, fuzzy logic seems the simplest and is the preferred for the


Hi Chris,

This sounds very cool, although, why are you so concerned about radar stealth, TEMPEST, radioactivity etc? You make it sound A LOT like a military/war UAV! Although I am not really qualified to say, I don't think a military UAV should use free GPL'd work -- its use should be peaceful. What do the project leaders think about this??


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